The purification of gases by means of physically acting absorbent solutions and, particularly, the removal of CO.sub.2 and H.sub.2 S from gases has been known for a long time. Processes of this kind have been described in the German Pat. No. 1,494,806 and in U.S. Pats. Nos. 3,531,917 and 3,710,546.
It is also known to regenerate the laden absorbent solution by a pressure relief, heating or stripping treatment or by a combination of such treatments.
Physically acting absorbent solutions which can be employed include particularly methanol or N-methylpyrrolidone (NMP). The gas scrubbers are usually operated at temperatures in the range of +60.degree. to -80.degree. C.
In scrubbing the gas, the absorbent solution absorbs not only impurities but also certain quantities of valuable gases.